Einstein's argument illustrated the contradiction between quantum mechanics as we know it and the assumption of "no-spooky-action-at-a-distance"
Einstein's opponents stated it is not possible to measure both the position and the momentum of a particle at the same time to complete accuracy. If someone measures the position of a particle, the particle is disturbed, so it's momentum changed.
, Einstein created the quantum theory of light,In March 1905.The idea that light exists as tiny packets, or particles, which he called photons. Later in 1905 came an extension of special relativity in which Einstein proved that energy and matter are linked in the most famous relationship in physics:E=mc2